The invention relates to an apparatus for pressing sheet-like printed products, in particular folded printed products, having a first pair of pressing rollers, with a first pressing roller and a second pressing roller, and having at least one further pair of pressing rollers, which is arranged downstream of the first pair of pressing rollers and has a third pressing roller and a fourth pressing roller, and having a drive mechanism for driving the pressing rollers.
Such an apparatus serves for pressing sheet-like printed products such as brochures, periodicals, flyers, in particular folded products, to form a flat body.
The intention is for such printed products to be stacked one upon the other for transportation or the like and to be bundled, stowed and transported as compact stacks which require as little space as possible.
It has been found that in particular folded printed products enclose considerable quantities of air between the pages, this air resulting in unnecessarily high and often uneven stacks during the stacking operation.
This is sometimes aggravated in that, in particular in the case of relatively stiff materials, the sheets which have been folded over along a folding edge tend to unfold.
Tests to press such a stack in a stacking apparatus have shown that it is relatively difficult for the air between the folded-over pages or the air between the individual printed products to be removed quickly in a short period of time.
The known pressing apparatuses are located upstream of the stacking apparatus in order for enclosed air to be pressed out and for the individual printed product to be pressed into a flat product which is as compact as possible.
It has become established practice for this to be carried out by two pairs of pressing rollers arranged one behind the other.
During operation the pressing rollers become contaminated. In particular if the printing on the printed products is still very fresh, printer's ink gets deposited on the surface of the pressing rollers. It is equally possible for bits of material emanating from cutting operations or other machining operations to settle on the surface of the pressing rollers.
In the case of a known apparatus, the two pairs of pressing rollers are designed as pairs of pressing rollers arranged one above the other and the two pairs of pressing rollers butt directly against one another. Since it is necessary for the distance between the pressing rollers of a respective pair to be adjusted dependent on the thickness of the printed product and for at least one roller of a pair of pressing rollers to be mounted in a resiliently or damping manner, in order to damp impacts which occur, for example, when passing over a folding edge, it has become established practice to arrange the respectively lower pressing roller of the pair of pressing rollers in a stationary manner and to provide the respectively upper pressing roller, which can be adjusted to a slight extent, with a resilient or damping member.
For reasons of accessibility, these components have been arranged on the top side of the uppermost pair of pressing rollers.
As will readily be understood by those skilled in the art, the term “drive belt(s)” as used herein and in the claims, refers to any type of endless drive member, including belts, chains, or cables.
This then results in the pressing rollers being barely accessible for cleaning purposes, with the need that the pairs of pressing rollers have to be dismantled for a cleaning operation.
This is very time-consuming and, following assembly, it is necessary to readjust the correct position of the pressing rollers.
It is therefore object of the present invention to provide an apparatus of the above mentioned type whose rollers can be cleaned easily.